Słyk Maria, Litoborski Marcin
Department of Medical Physics, Greater Poland Cancer Centre.
Rep Pract Oncol Radiother. 2010 Oct 12;15(5):132-7. doi: 10.1016/j.rpor.2010.08.007. eCollection 2010.
The investigation of the irradiation time calculation accuracy of the GGPB algorithm used for IORT.
Conventionally, breast conserving therapy consists of breast conserving surgery followed by postoperative whole breast irradiation and boost. The use of intraoperative radiotherapy (IORT) enables the boost to be delivered already during the surgery. In this case, the treatment dose for IORT can be calculated by use of General Gaussian Pencil Beam (GGPB) algorithm, which is implemented in TPS Eclipse.
PDDs and OFs for electron beams from Mobetron and all available applicators were measured in order to configure the GGPB algorithm. Afterwards, the irradiation times for the prescribed dose of 3 Gy were calculated by means of it. The results of calculations were verified in the water phantom using the Marcus ionization chamber.
The results differed between energies. For 6 MeV the irradiation times calculated by the GGPB algorithm were correct, for the energy of 9 MeV they were too small and for the energy of 4 MeV they were too large for applicators with smaller diameters, while acceptable for the remaining ones.
The GGPB algorithm can be used in intraoperative radiotherapy for energy and applicator sets for which no significant difference between the measured and the prescribed dose was obtained. For the rest of energy-applicator sets the configuration should be verified and possibly repeated.
研究用于术中放疗（IORT）的通用高斯笔形束（GGPB）算法的照射时间计算准确性。
传统上，保乳治疗包括保乳手术，随后进行术后全乳照射和瘤床加量照射。术中放疗（IORT）的应用使得瘤床加量照射能够在手术期间进行。在这种情况下，IORT的治疗剂量可通过TPS Eclipse中实现的通用高斯笔形束（GGPB）算法来计算。
测量了来自Mobetron的电子束以及所有可用施源器的百分深度剂量（PDD）和输出因子（OF），以便配置GGPB算法。之后，通过该算法计算规定剂量3 Gy的照射时间。计算结果在水模体中使用Marcus电离室进行验证。
不同能量的结果有所不同。对于6 MeV，GGPB算法计算出的照射时间是正确的；对于9 MeV的能量，照射时间过小；对于4 MeV的能量，对于直径较小的施源器，照射时间过大，而对于其余施源器则是可接受的。
GGPB算法可用于术中放疗中测量剂量与规定剂量无显著差异的能量和施源器组合。对于其余的能量 - 施源器组合，应验证配置并可能重复进行。
